20789475809 has 2 divisors, whose sum is σ = 20789475810. Its totient is φ = 20789475808.

The previous prime is 20789475799. The next prime is 20789475829. The reversal of 20789475809 is 90857498702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19683248209 + 1106227600 = 140297^2 + 33260^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20789475809 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20789475829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10394737904 + 10394737905.

It is an arithmetic number, because the mean of its divisors is an integer number (10394737905).

Almost surely, 2^20789475809 is an apocalyptic number.

It is an amenable number.

20789475809 is a deficient number, since it is larger than the sum of its proper divisors (1).

20789475809 is an equidigital number, since it uses as much as digits as its factorization.

20789475809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10160640, while the sum is 59.

The spelling of 20789475809 in words is "twenty billion, seven hundred eighty-nine million, four hundred seventy-five thousand, eight hundred nine".